ds is 4 months and loves loves LOVES to stand up - cue sore arms from holding him under the armpits for hours while he stands up and takes mini steps/kicks legs etc. he gets bored lying down on gym and he's just starting to sit unaided for a few seconds. a baby walker seems like a good option but i've got a vague feeling i've heard somewhere they're not good for babies' development, or something... is that true? has anyone got one and does it get a lot of use? we have sanded floors and rugs - will it even work?